1. Field of the Invention
The invention relates to a fluid injector and a method of manufacturing the same; in particular, a fluid injector with enhanced efficiency and lifetime.
2. Description of the Related Art
Normally, fluid injectors are applied in inkjet printers, fuel injectors, and other devices. Among inkjet printers presently known and used, injection by a thermally driven bubble has been most successful due to its simplicity and relatively low cost.
FIG. 1 is a conventional monolithic fluid injector 1 as disclosed in U.S. Pat. No. 6,102,530. A structural layer 12 is formed on a silicon substrate 10. A fluid chamber 14 is formed between the silicon substrate 10 and the structural layer 12 to receive fluid 26. A first heater 20 and a second heater 22 are disposed on the structural layer 12. The first heater 20 generates a first bubble 30 in the chamber 14, and the second heater 22 generates a second bubble 32 in the chamber 14 to eject the fluid 26 from the chamber 14.
The monolithic fluid injector 1 includes a virtual valve, and is arranged in a high-density array. Furthermore, the monolithic fluid injector 1 exhibits low intermixing and low heat-loss. Additionally, there is no need to connect an additional nozzle plate to the monolithic fluid injector. As a result, the cost of the monolithic fluid injector 1 is reduced.
In the conventional monolithic fluid injector 1, however, the structural layer 12 mainly consists of silicon oxide with low stress. During manufacture, the thickness of the structural layer 12 is kept within a predetermined range; therefore, the lifetime of the entire structure of the conventional monolithic fluid injector 1 is also limited. Furthermore, since the thickness of the structural layer 12 is insufficient, the direction of injected fluid is not consistent. Additionally, after a micro fluid droplet leaves the orifice, the fluid reflows into the fluid chamber and diffuses to the surface of the fluid injector device causing overflow, and is detrimental to the next injection.